There are a number of technologies that I'm interested in right now (machine learning, "NoSQL" databases, graph databases, computer vision analysis, Node.js, amongst others) so I will just casually read about these things as time goes by. When the time comes for a new project I'll try to use one of them (but usually only one, too many new technologies and you're spending too much time just learning APIs). This has helped me to continually pick up some new techniques. Not sure if this is a silver bullet but it's been working pretty well for me. I try not to stress too much about jumping on the latest tech - I'd much rather wait and have others try it out and let me know if it does/doesn't work!